Pub Date : 2023-01-27DOI: 10.18186/thermal.1243512
A. Datta, P. Halder
The field synergy study is carried out using three oxide nanofluids impinging circular jet on the horizontal circular disc to analyse the synergetic interaction of cooling processes between temperature and flows fields. The h eat transfer effect o f the nanofluid is examined by rising the Reynolds number and the nanoparticle concentration depending on field synergy number. For jet impinged cooling process, the scale of synergy between the nanofluid flow speed and temperature is decayed with the increase of Reynolds number. Hence, it is contributed to a lower heat transfer efficiency of the nanofluid. Whe reas, the scale of synergy between the nanofluid flow speed and temperature can be enhanced by rising the particle concentration. Thus, the heat transfer efficiency of the nanofluid is increased. Analysis showed that Al2O3 nanofluid has the maximum relative field synergy among selected three oxide nanofluids. It is evident that the nanoparticle concentration, nanoparticle material and Reynolds number have significant effect on the heat transfer augmentation. In addition, the study is explored by varying jet-disk spacing. Moreover, the investigation has shown that the reducing heat transfer effect for the materials is Al2O3, CuO and TiO2 subsequently. It is revealed that the heat enhancement is higher for smaller nanoparticle’s diameter (i.e., 20 nm) than bigger nanoparticle’s diameter (i.e., 80 nm) of the same material.
{"title":"Field-synergy and nanoparticle’s diameter analysis on circular jet impingement using three oxide–water-based nanofluids","authors":"A. Datta, P. Halder","doi":"10.18186/thermal.1243512","DOIUrl":"https://doi.org/10.18186/thermal.1243512","url":null,"abstract":"The field synergy study is carried out using three oxide nanofluids impinging circular jet on the horizontal circular disc to analyse the synergetic interaction of cooling processes between temperature and flows fields. The h eat transfer effect o f the nanofluid is examined by rising the Reynolds number and the nanoparticle concentration depending on field synergy number. For jet impinged cooling process, the scale of synergy between the nanofluid flow speed and temperature is decayed with the increase of Reynolds number. Hence, it is contributed to a lower heat transfer efficiency of the nanofluid. Whe reas, the scale of synergy between the nanofluid flow speed and temperature can be enhanced by rising the particle concentration. Thus, the heat transfer efficiency of the nanofluid is increased. Analysis showed that Al2O3 nanofluid has the maximum relative field synergy among selected three oxide nanofluids. It is evident that the nanoparticle concentration, nanoparticle material and Reynolds number have significant effect on the heat transfer augmentation. In addition, the study is explored by varying jet-disk spacing. Moreover, the investigation has shown that the reducing heat transfer effect for the materials is Al2O3, CuO and TiO2 subsequently. It is revealed that the heat enhancement is higher for smaller nanoparticle’s diameter (i.e., 20 nm) than bigger nanoparticle’s diameter (i.e., 80 nm) of the same material.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41480588","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-27DOI: 10.18186/thermal.1243398
R. Barai, Devesh Kumar, A. Wankhade
Energy is a key aspect of any country’s economic development. Improving heat transfer performance leads to saving energy. Nanotechnology has a key role to play in optimizing heat exchangers. Fluids containing nanosized particles are called nanofluids. Nanofluids have higher thermal conductivity than typical liquids. This paper outlines current research on convective heat transfer performance, thermophysical properties, particle size, and volume concentration effects in nanofluid studies. M easurement m ethods f ort h ermal conductivity and correlations used by earlier researchers to determine thermal conductivity are also encompassed. The main applications of nanofluids as liibricants a nd radiator systems to improve the efficiency of he at removal fr om ve hicle en gines ha ve al so be en emphasized. Results suggest that by using a larger size of particle some drawbacks include particle sedimentation, clogging, erosion, stability, and increasing pressure drop. Enhancing thermal conductivity with optimum volume concentration. Improving the efficiency of heat exchange systems is one of the possible ways to reduce energy consumption. The need for optimum concentration of nanofluids is required. The Problem of stability, corrosion, and erosion arrived by increasing the volume concentration of nanoparticles in a nanofluid.
{"title":"Heat transfer performance of nanofluids in heat exchanger: a review","authors":"R. Barai, Devesh Kumar, A. Wankhade","doi":"10.18186/thermal.1243398","DOIUrl":"https://doi.org/10.18186/thermal.1243398","url":null,"abstract":"Energy is a key aspect of any country’s economic development. Improving heat transfer performance leads to saving energy. Nanotechnology has a key role to play in optimizing heat exchangers. Fluids containing nanosized particles are called nanofluids. Nanofluids have higher thermal conductivity than typical liquids. This paper outlines current research on convective heat transfer performance, thermophysical properties, particle size, and volume concentration effects in nanofluid studies. M easurement m ethods f ort h ermal conductivity and correlations used by earlier researchers to determine thermal conductivity are also encompassed. The main applications of nanofluids as liibricants a nd radiator systems to improve the efficiency of he at removal fr om ve hicle en gines ha ve al so be en emphasized. Results suggest that by using a larger size of particle some drawbacks include particle sedimentation, clogging, erosion, stability, and increasing pressure drop. Enhancing thermal conductivity with optimum volume concentration. Improving the efficiency of heat exchange systems is one of the possible ways to reduce energy consumption. The need for optimum concentration of nanofluids is required. The Problem of stability, corrosion, and erosion arrived by increasing the volume concentration of nanoparticles in a nanofluid.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46587250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-27DOI: 10.18186/thermal.1243498
M. Azzam, Zabayyan Qaq, M. Orhan
This study provides a step-by-step, up-to-date fuel cell fundamentals, thermodynamic and electrochemical principles, and system evaluation factors via a case study of a 10-kW alkaline fuel cell designed to operate in space applications. The system also produces 100 kg of pure water and 5.5 kW of heat. The system is modelled using MATLAB and ANSYS Fluent. Then, the model is verified with theoretical and experimental results from the literature. A parametric study of various design and operating parameters, and material selection is carried out to optimize the overall performance. A net output voltage of 0.8 V is obtained at 150 mAcm-2 current density, which yields an overall efficiency of 75%. The results indicate that increasing the electrolyte thickness or operating temperature results in a lower net voltage output. Additionally, improving the performance of a fuel cell through the bipolar plate can be achieved by understanding the contribution of different parameters towards minimizing the pressure drop across the bipolar plate. It is found that implementing an optimized selection of fluid flow rate, channel width, channel depth, number of channels and current density minimize the pressure drop throughout the bipolar plate. Relative humidity has a significant effect on the pressure drop. Results indicate that increasing the relative humidity consequentially rises the pressure drop. Finally, the CFD simulation illustrates that the end-zones in the bipolar plate accumulates fluid due to the nature of stagnation at those locations. Thus, total pressure at those locations is the highest. One of the major contributions here is studying the effect of KOH concentration on the performance of the AFC at different operating temperatures. In addition, a wide range of design and operating parameters were analysed to understand their effect on the overall performance of the fuel cell.
{"title":"Design and analysis of an alkaline fuel cell","authors":"M. Azzam, Zabayyan Qaq, M. Orhan","doi":"10.18186/thermal.1243498","DOIUrl":"https://doi.org/10.18186/thermal.1243498","url":null,"abstract":"This study provides a step-by-step, up-to-date fuel cell fundamentals, thermodynamic and electrochemical principles, and system evaluation factors via a case study of a 10-kW alkaline fuel cell designed to operate in space applications. The system also produces 100 kg of pure water and 5.5 kW of heat. The system is modelled using MATLAB and ANSYS Fluent. Then, the model is verified with theoretical and experimental results from the literature. A parametric study of various design and operating parameters, and material selection is carried out to optimize the overall performance. A net output voltage of 0.8 V is obtained at 150 mAcm-2 current density, which yields an overall efficiency of 75%. The results indicate that increasing the electrolyte thickness or operating temperature results in a lower net voltage output. Additionally, improving the performance of a fuel cell through the bipolar plate can be achieved by understanding the contribution of different parameters towards minimizing the pressure drop across the bipolar plate. It is found that implementing an optimized selection of fluid flow rate, channel width, channel depth, number of channels and current density minimize the pressure drop throughout the bipolar plate. Relative humidity has a significant effect on the pressure drop. Results indicate that increasing the relative humidity consequentially rises the pressure drop. Finally, the CFD simulation illustrates that the end-zones in the bipolar plate accumulates fluid due to the nature of stagnation at those locations. Thus, total pressure at those locations is the highest. One of the major contributions here is studying the effect of KOH concentration on the performance of the AFC at different operating temperatures. In addition, a wide range of design and operating parameters were analysed to understand their effect on the overall performance of the fuel cell.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49304593","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-26DOI: 10.18186/thermal.1242844
Ajit Katiyar, N. Gupta
In this study, the effect of different concentration of the Aluminium oxide-based nanofluid on the performance of Solar Desalination system was discussed. The Aluminium Oxide was used in different concentrations 1%, 2% and 6% on weight basis. The flow rate was also varied and its effect on the system efficiency was discussed. The nanofluid was compared with the water and there was improvement occurred in the efficiency during variation of incident radiation. With an increase in the concentration of Aluminium oxide nanoparticles, improvement in the efficiency was attained. More efficiency was attained at 6% nanoparticles addition with compared to 1% and 2%. With an increase in mass flow rate of the fluid, the nanofluid also showed better performance in terms of improvement in the efficiency.
{"title":"Effect of different aluminium oxide based nanofluid concentrations on the efficiency of solar water desalination system","authors":"Ajit Katiyar, N. Gupta","doi":"10.18186/thermal.1242844","DOIUrl":"https://doi.org/10.18186/thermal.1242844","url":null,"abstract":"In this study, the effect of different concentration of the Aluminium oxide-based nanofluid on the performance of Solar Desalination system was discussed. The Aluminium Oxide was used in different concentrations 1%, 2% and 6% on weight basis. The flow rate was also varied and its effect on the system efficiency was discussed. The nanofluid was compared with the water and there was improvement occurred in the efficiency during variation of incident radiation. With an increase in the concentration of Aluminium oxide nanoparticles, improvement in the efficiency was attained. More efficiency was attained at 6% nanoparticles addition with compared to 1% and 2%. With an increase in mass flow rate of the fluid, the nanofluid also showed better performance in terms of improvement in the efficiency.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47045156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-26DOI: 10.18186/thermal.1242919
H. Aygun
In this study, parametric cycle analysis of a conceptual turbojet engine with an afterburner (TJEAB) was conducted at sea level conditions-zero Mach. Based on this analysis, exergetic sustainability parameters of TJEAB were scrutinized for military mode (MM) and afterburner mode (ABM). Constitutively, several design parameters of TJEAB were chosen so as to optimize performance and exergetic parameters which consist of specific fuel consumption (SFC), overall efficiency, exergy efficiency, environmental effect factor (EEF) and exergetic sustainability index (ESI). In this context, compressor pressure ratio (CPR), turbine inlet temperature (TIT) were preferred due to high effect of these variables on engine performance. CPR ranges from 4 to 11 whereas TIT varies from 1150 K to 1550 K. According to optimization of performance parameters, minimum SFC was achieved as 28.59 g/kN.s at MM and 43.95 g/kN.s at ABM. On the other hand, maximum overall efficiency is determined as to be 13.07 % at MM and to be 8.5 % at ABM. As for exergetic parameters, exergy efficiency was calculated as maximum with 30.85 % at MM and 23.2 %at ABM. Finally, maximum exergetic sustainability index of TJEAB was computed as 0.446 at MM and 0.269 at ABM. It is thought that energetic and exergetic parameters analyzed in this analysis could guide in designing turbojet engines in terms of lower fuel consumption thereby environmental-benign.
{"title":"Optimization of energy and exergy parameters for a conceptual after burning turbojet engine","authors":"H. Aygun","doi":"10.18186/thermal.1242919","DOIUrl":"https://doi.org/10.18186/thermal.1242919","url":null,"abstract":"In this study, parametric cycle analysis of a conceptual turbojet engine with an afterburner (TJEAB) was conducted at sea level conditions-zero Mach. Based on this analysis, exergetic sustainability parameters of TJEAB were scrutinized for military mode (MM) and afterburner mode (ABM). Constitutively, several design parameters of TJEAB were chosen so as to optimize performance and exergetic parameters which consist of specific fuel consumption (SFC), overall efficiency, exergy efficiency, environmental effect factor (EEF) and exergetic sustainability index (ESI). In this context, compressor pressure ratio (CPR), turbine inlet temperature (TIT) were preferred due to high effect of these variables on engine performance. CPR ranges from 4 to 11 whereas TIT varies from 1150 K to 1550 K. According to optimization of performance parameters, minimum SFC was achieved as 28.59 g/kN.s at MM and 43.95 g/kN.s at ABM. On the other hand, maximum overall efficiency is determined as to be 13.07 % at MM and to be 8.5 % at ABM. As for exergetic parameters, exergy efficiency was calculated as maximum with 30.85 % at MM and 23.2 %at ABM. Finally, maximum exergetic sustainability index of TJEAB was computed as 0.446 at MM and 0.269 at ABM. It is thought that energetic and exergetic parameters analyzed in this analysis could guide in designing turbojet engines in terms of lower fuel consumption thereby environmental-benign.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45153111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-26DOI: 10.18186/thermal.1242832
K. Madan, O. Singh
In the published studies, to the best of the authors’ understanding, the grey Taguchi-based statistical technique has not been applied for the optimization of combined gas-steam power plants. In view of this, seven essential input parameters namely compressor inlet air temperature, pressure ratio, fuel temperature, volumetric flow rate of fuel, gas turbine maximum temperature, compressor efficiency, and turbine efficiency are chosen with the aim of determining the optimal combination of design variables that maximize the net power generation, thermal efficiency, exergetic effciency, and minimize the specific fuel consumption. Also, the impact weight of each parameter on output indicators has been evaluated. While the Taguchi approach helps to create an orthogonal array of L27 (3^7), the ANOVA method determines the contribution of each input argument on the objective function. Unlike the Taguchi and ANOVA optimization methodology, the grey relational analysis is performed to transform the multi-objective function into a single objective by way of estimating its grey relational grade. The most favorable combination of input parameters is determined as A1B1C1D1E3F3G3 and under this state, the optimum values of power generation, thermal efficiency, exergetic efficiency, and specific fuel consumption are found to be 259911 kW, 64.9 %, 66.27 %, and 0.1839 kg/kWh respectively. Moreover, the contribution ratio on the output characteristic of the combined cycle is found to be maximum for turbine efficiency (42.41 %) and minimum for fuel temperature (0.59 %). The effectiveness of the grey-Taguchi method is acknowledged and validated using an artificial neural network technique in MATLAB.
{"title":"Comparative analysis and optimization of thermodynamic behavior of combined gas-steam power plant using grey-taguchi and artificial neural network","authors":"K. Madan, O. Singh","doi":"10.18186/thermal.1242832","DOIUrl":"https://doi.org/10.18186/thermal.1242832","url":null,"abstract":"In the published studies, to the best of the authors’ understanding, the grey Taguchi-based statistical technique has not been applied for the optimization of combined gas-steam power plants. In view of this, seven essential input parameters namely compressor inlet air temperature, pressure ratio, fuel temperature, volumetric flow rate of fuel, gas turbine maximum temperature, compressor efficiency, and turbine efficiency are chosen with the aim of determining the optimal combination of design variables that maximize the net power generation, thermal efficiency, exergetic effciency, and minimize the specific fuel consumption. Also, the impact weight of each parameter on output indicators has been evaluated. While the Taguchi approach helps to create an orthogonal array of L27 (3^7), the ANOVA method determines the contribution of each input argument on the objective function. Unlike the Taguchi and ANOVA optimization methodology, the grey relational analysis is performed to transform the multi-objective function into a single objective by way of estimating its grey relational grade. The most favorable combination of input parameters is determined as A1B1C1D1E3F3G3 and under this state, the optimum values of power generation, thermal efficiency, exergetic efficiency, and specific fuel consumption are found to be 259911 kW, 64.9 %, 66.27 %, and 0.1839 kg/kWh respectively. Moreover, the contribution ratio on the output characteristic of the combined cycle is found to be maximum for turbine efficiency (42.41 %) and minimum for fuel temperature (0.59 %). The effectiveness of the grey-Taguchi method is acknowledged and validated using an artificial neural network technique in MATLAB.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48676338","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-26DOI: 10.18186/thermal.1242825
Anuj Raturi, R. Patel, D. Singh
A sensitivity study for N similar partly enclosed with photovoltaic thermal flat plate collectors with a series connection (N-PVT-FPCs) has been carried out in this research study. The analysis has been done for a typical day of May, wherein data for the ambient conditions of New Delhi (India) has been received from the India metrological department (IMD), Pune, India. In addition, further computational work has been carried out on the MATLAB programme for the daily heat gain of N-PVT-FPCs. One-at-a-time (OAT) methodology has been used for the sensitivity analysis. From the sensitivity analysis, it has been found that the heat gain from the proposed system is more sensitive with respect to the number of collectors (N) followed by inclination angle, mass flow rate (MFR) and packing factor (PF). The sensitivity figure has been found to be 0.08, 0.17, 0.25 and 0.94 for daily heat gain of N-PVT-FPCs with respect to PF, MFR, inclination angle and N, respectively.
{"title":"A sensitivity study for n similar partly enclosed with photovoltaic thermal flat plate collectors having series connection","authors":"Anuj Raturi, R. Patel, D. Singh","doi":"10.18186/thermal.1242825","DOIUrl":"https://doi.org/10.18186/thermal.1242825","url":null,"abstract":"A sensitivity study for N similar partly enclosed with photovoltaic thermal flat plate collectors with a series connection (N-PVT-FPCs) has been carried out in this research study. The analysis has been done for a typical day of May, wherein data for the ambient conditions of New Delhi (India) has been received from the India metrological department (IMD), Pune, India. In addition, further computational work has been carried out on the MATLAB programme for the daily heat gain of N-PVT-FPCs. One-at-a-time (OAT) methodology has been used for the sensitivity analysis. From the sensitivity analysis, it has been found that the heat gain from the proposed system is more sensitive with respect to the number of collectors (N) followed by inclination angle, mass flow rate (MFR) and packing factor (PF). The sensitivity figure has been found to be 0.08, 0.17, 0.25 and 0.94 for daily heat gain of N-PVT-FPCs with respect to PF, MFR, inclination angle and N, respectively.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43504774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-20DOI: 10.18186/thermal.1239793
Saad M. Najim, A. Hussein, S. Danook
The objective of this paper is to study the effect of nanofluid on the performance of the heat exchanger, as well as the heat transfer rate, coefficient of total heat transfer, friction influence and average Nusselt number, and thermal efficiency factor and has been investigated and discussed. In this work, the output heat transfer of Fe3O4/water nanofluid through shell and tube heat exchanger has been numerically investigated under laminar flow. CFD simulations with ANSYS FLUENT 2020R1 were used adopting finite volume approach to solve the governing equations. Numerical calculations were carried out for Reynolds numbers ranging from 200 to 1400, with nanoparticles as the volume fraction (0.2% and 0.35%). The results show that the augmentation in increase Nusselt number and amount of heat transfer rate and the efficiency of nanofluid at the concentration of 0.35% are approximately 19%, 25% and 12% respectively. It was observed through the results that the friction decreases as the Reynolds number increase.
{"title":"Performance improvement of shell and tube heat exchanger by using Fe3O4/water nanofluid","authors":"Saad M. Najim, A. Hussein, S. Danook","doi":"10.18186/thermal.1239793","DOIUrl":"https://doi.org/10.18186/thermal.1239793","url":null,"abstract":"The objective of this paper is to study the effect of nanofluid on the performance of the heat exchanger, as well as the heat transfer rate, coefficient of total heat transfer, friction influence and average Nusselt number, and thermal efficiency factor and has been investigated and discussed. In this work, the output heat transfer of Fe3O4/water nanofluid through shell and tube heat exchanger has been numerically investigated under laminar flow. CFD simulations with ANSYS FLUENT 2020R1 were used adopting finite volume approach to solve the governing equations. Numerical calculations were carried out for Reynolds numbers ranging from 200 to 1400, with nanoparticles as the volume fraction (0.2% and 0.35%). The results show that the augmentation in increase Nusselt number and amount of heat transfer rate and the efficiency of nanofluid at the concentration of 0.35% are approximately 19%, 25% and 12% respectively. It was observed through the results that the friction decreases as the Reynolds number increase.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42648216","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-11DOI: 10.18186/thermal.1232431
B. Mahfoud, M. Moussaoui
In this study, the Generalized Integral Transformation Technique (GITT) is used to describe the effect of buoyancy force and magnetic field on the vortex breakdown process generated by the rotation of an electrically conductive fluid. A magnetic field is positioned vertically to stabilize the swirling flow caused by the rotation of the bottom disc of a cylindrical recipient. Three fluids were compared in this study where the range of Richardson number is 0 ≤Ri ≤2.0. When the temperature difference is greater than Ri = 0.1, many layers become visible. These stratified flu id layers act as thermal insulators. In the case of stratification, the increased magnetic field reduces the total number of layers formed in the fluid. The influence of gradient temperature on the distribution of the layers generated is discussed. The limitations between the multilayer structure and the monolayer structure for three fluids are calculated as a function of the flow parameters.
{"title":"Buoyancy force and magnetic field effects on laminar vortex breakdown and fluid layers","authors":"B. Mahfoud, M. Moussaoui","doi":"10.18186/thermal.1232431","DOIUrl":"https://doi.org/10.18186/thermal.1232431","url":null,"abstract":"In this study, the Generalized Integral Transformation Technique (GITT) is used to describe the effect of buoyancy force and magnetic field on the vortex breakdown process generated by the rotation of an electrically conductive fluid. A magnetic field is positioned vertically to stabilize the swirling flow caused by the rotation of the bottom disc of a cylindrical recipient. Three fluids were compared in this study where the range of Richardson number is 0 ≤Ri ≤2.0. When the temperature difference is greater than Ri = 0.1, many layers become visible. These stratified flu id layers act as thermal insulators. In the case of stratification, the increased magnetic field reduces the total number of layers formed in the fluid. The influence of gradient temperature on the distribution of the layers generated is discussed. The limitations between the multilayer structure and the monolayer structure for three fluids are calculated as a function of the flow parameters.","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48339614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-01-11DOI: 10.18186/thermal.1232462
Prateek D. Malwe, B. Gawali, Rustam Dhalait, Nandkishor S. Deshmukh
The world is facing the problems of the energy crisis. Thermal analysis and energy conservation of the engineering devices help to improve their performance. This paper conducted an experimental investigation for the performance analysis and exergy assessment of an Inertance Pulse Tube Cryocooler (IPTC) that uses working fluid -helium operated between 80 K cold end side temperature and room temperature.The variation of the different performance parameters like the effect of charge pressure, pulse tube volume, pulse tube length, etc., and its effect on the refrigerating effect isdescribed graphically. Exergy analysis involves the use and concepts of energy andexergy balances, enthalpy, entropy, and exergy calculations at various stages in thesystem. Exergy analysis identifies the zones of key exergy destruction that occurs insidethe system, which afterward can be subjected to its minimization to amend the systemperformance. The actual exergy efficiency value calculated for the overall system is 21.30 %. The decreasing order of exergy efficiency among the different components is acompressor (38.79 %), a hot end heat exchanger (6.19 %), regenerator, pulse tube andinertance tube (6 %), and cold end heat exchanger (2.70 %).
{"title":"Performance analysis and exergy assessment of an inertance pulse tube cryocooler","authors":"Prateek D. Malwe, B. Gawali, Rustam Dhalait, Nandkishor S. Deshmukh","doi":"10.18186/thermal.1232462","DOIUrl":"https://doi.org/10.18186/thermal.1232462","url":null,"abstract":"The world is facing the problems of the energy crisis. Thermal analysis and energy conservation of the engineering devices help to improve their performance. This paper conducted an experimental investigation for the performance analysis and exergy assessment of an Inertance Pulse Tube Cryocooler (IPTC) that uses working fluid -helium operated between 80 K cold end side temperature and room temperature.The variation of the different performance parameters like the effect of charge pressure, pulse tube volume, pulse tube length, etc., and its effect on the refrigerating effect isdescribed graphically. Exergy analysis involves the use and concepts of energy andexergy balances, enthalpy, entropy, and exergy calculations at various stages in thesystem. Exergy analysis identifies the zones of key exergy destruction that occurs insidethe system, which afterward can be subjected to its minimization to amend the systemperformance. The actual exergy efficiency value calculated for the overall system is 21.30 %. The decreasing order of exergy efficiency among the different components is acompressor (38.79 %), a hot end heat exchanger (6.19 %), regenerator, pulse tube andinertance tube (6 %), and cold end heat exchanger (2.70 %).","PeriodicalId":45841,"journal":{"name":"Journal of Thermal Engineering","volume":" ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42603821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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